Project on Mac and PC showing changes on one side only

[mythicalcity]

Hi everyone, I'm trying to work on a project on an external drive between mac and PC computers (and the Mac and PC versions of Sourcetree). On one OS (I think whichever originally pulled the repo) everything works great, but on the other OS sourcetree shows hundreds of the project files as changed yet without any changes in the diff window. None of these files have been changed by us, and the changes don't show up in sourcetree on the other OS. 

This is the latest versions of sourcetree on OXS 10.15.4 and Windows 10 Pro. The project is a Unity game.